1. Technical Field
The present invention relates to an endoscopic imaging device and an endoscopic apparatus.
2. Related Art
An endoscope with a typical configuration has an elongated endoscope insertion portion to be inserted into a subject to be inspected, and an illumination optical system for illuminating an area to be observed and an imaging optical system for imaging the area to be observed are disposed in a front end portion of the endoscope insertion portion. In the illumination optical system, a light guide which is formed out of a bundle of optical fibers is provided to extend into the endoscope insertion portion, and a base end side of the light guide is coupled with a light source unit so that light from the light source unit can be guided to the front end portion of the endoscope and emitted as illumination light from the front end portion of the endoscope. In the imaging optical system, an objective lens is disposed in the front end portion of the endoscope, and an imaging element is disposed in the front end portion of the endoscope to be located in the position where the objective lens will focus an image. Thus, an observed image of the area to be observed is generated.
An example of the aforementioned endoscope includes an endoscope having an imaging device in which a triangular prism is disposed on an imaging surface of an imaging element with a transmissive protective substrate interposed therebetween (see JP-A-2007-260190). As described in JP-A-2007-260190, a heater is pasted to the triangular prism so as to prevent dew condensation from occurring in the transmissive protective substrate when the imaging element is powered on. In this configuration, the dew-condensation preventing heater which does not have any direct relation with imaging is still provided to be connected through a dedicated wiring from a peripheral circuit board or the like. Accordingly, there is a disadvantage that additional components are required in a manufacturing process, and there is a disadvantage that an extra installation space is required. In addition, the on/off timing of the heater must be controlled. Therefore, the configuration of the imaging device as a whole becomes complicated.
An object of the invention is to provide an endoscopic imaging device in which occurrence of dew condensation on a transmissive protective substrate is prevented with a simple configuration so that a good field of view is always secured, and an endoscopic apparatus having the endoscopic imaging device.